> it's totally possible to (by, say, 2036) train 100% of teachers to perform at a 90th percentile as compared to teachers from 2026. That's how improvement works, which is what people are describing here.

I doubt you can pull this off unless you’re willing (and able) to fire at least 25% of teachers who appear not willing (and under strong unions cannot be required) to outperform the current 90th percentile teacher.

There are great teachers; there are also entirely lazy/entitled teachers who will never willingly be at the performance of the current top 10%.

Okay, then by 2036 the curriculum and standards of teaching will have been updated too, the expectation of what teachers will be able to teach will have been updated too, the competence of students will have been updated, and the hidden expectation will still be that every teacher can do as well as the "gifted" teachers of 2036. You can predict that this is what will happen because this has been happening for the last century. Up until the last five years student test scores were improving, and if you believe that teacher performance is at all linked to student performance, then improving student test scores ought to draw from teachers getting better too, but that's not good enough. Why? Because the concern - after a baseline is established - is seeking exceptional performance, which definitionally cannot be made routine.

who will train them ? average trainers. it's a chicken/egg problem